Green-Light-Driven Poly(N-isopropylacrylamide-acrylamide)/Fe3O4 Nanocomposite Hydrogel Actuators

Light-responsive hydrogel actuators show attractive biomedical applications for in vivo drug delivery tool, surgical tissue repair operation, and vascular cleaning due to its non-contact, rapid, precise, and remote spatial control of light. Conventional visible-light-responsive hydrogels contain special chemical structure or groups, and the difficulty in synthesis results in that few can be applied to fabricate visible-light-driven hydrogel actuators. In this study, based on photothermal effect, surface-modified Fe3O4 nanoparticles were incorporated into poly(N-isopropylacrylamide-acrylamide) hydrogel by UV photopolymerization, which revealed excellent green-light-responsive volume change. Under a laser irradiation of 200 mW at 520 nm, the bending angle deformation of hydrogel strips with 2.62 wt% Fe3O4 reached 107.8 degrees. Strip-shaped hydrogel actuators could be applied to transport tiny objects. Furthermore, a boomerang-like hydrogel actuator was designed and fabricated to drive floating foam on water. By 12 cycles of continuous laser on-off irradiation to a hydrogel actuator underwater, a circular returning movement of the float was accomplished. The study on driving a float using visible-light-triggered hydrogel actuators provides a new idea for the design of light-driven biomedical devices and soft robots.

Automated summary

In this study, Fe3O4 nanoparticles were incorporated into poly(N-isopropylacrylamide-acrylamide) hydrogel to achieve green-light-responsive volume change through photothermal effect. A boomerang-like hydrogel actuator was also designed and fabricated, successfully driving a floating foam in water in a circular returning movement.